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nitrl Sintra @aient @Wina Letters Patent No. 99,317, dated February l, 1870.

IMPRovBMENT IN BIT-STOCKS The Schedule referred to in these Lettera Patent and making `ptn-1: of the same.

To all whom 'it may concern.-

Be itknown that I, ROYALL S. HILDRETH, of South Adams, in the county of Berkshire, and State of Massachusetts, have invented a new and useful Improvement in Bit-Stocks; and I do hereby declare that the following is a full, clear, and exact description thereof, which will enable others skilled in the art to make and n'se the same, reference being had to the accompanying drawings, forming part of this specification.

This invention relates to new and useful improvements in bit-stocks or braces, for holding and operating boring-bits; and

The invention consists in the construction, arrangement, and combination of parts, consisting of pivoted jaws, a sliding sleeve, and spring, whereby said jaws are operated, vso as to fasten and release the bit, as hereinafter' more fully described.

InL the drawing- Figure 1 represents a sectional view of a bit-stock,- const-ructed according to my invention.

Figure 2 represents the fastening-jaws detached.

Figure 3 is an end view of the stock.

Similar letters of reference indicate corresponding parts.

The extension-stock is formed by means of two tubular parts, B and C, which are connected together by the handle-piece D.

The handle-piece D is made adjustable in the parts, by means of the thumb-screws E E, as seen in the drawings.

By'extending the hand-piece from the parts B C, the sweep or leverage of the stock may be increased. With small bits, requiring but a slight exertion of power, the stock would be used as seen in the drawing. By this arrangement, the stock may be adjusted to suit the power to be exerted.

F F represent jaws in the mouth G of the stock,

which are hinged on apin, as seen at H, so that they may spread at their outer ends, or be forced inward.

I is a spring between them, which forces them apart.

J is a sleeve, which slides on the neck of' the stock, and forces the jaws F inward, when it moves toward the mouth ofthe stock.

K is a spiral spring, around the neck of the stock. One end o f it bears against the collar L, and the other end bears against the sleeve with aconstant pressure, and serves to keep the jaws closed. The lower portion of the sleeve is chambered out, so that it encloses one part of the spring, as seen in the drawing.

'lhe movement ofthe sleeve outward is limited by the small flanges m, on the outer ends of the jaws.

The angles of the bit-socket are notched out, as seen in fig. 2, to catch the bit, and prevent its withdrawal until the sleeve is pressed down.

The sleeve being forced outward by the spring, with a constant pressure, it will be seen that the jaws will be kept closed within the mouth-socket, and the bit firmly held at all times.

The facility with which boring-bits may be fastened in the-stock, and removed therefrom, renders this a most desirable arrangement; and when it is combined with an extension-stock, little -isleft to be desired in this direction.

Having thus described my invention,

I claim as new, and desire to secure by Letters Patent- The sleeve J, spring K, and the jaws F, when the same are constructed, arranged, and operated in combination withva bit-stock, substantially as and for the purposes herein shown and described.

ROYALL S. HILDRETH.

Witnesses:

R. B. RICHMOND, JESSE A. FIELD. 

